The goal of this set of analyses is to take a deeper dive into the 2019 Seattle calls for service data. To follow up on the preliminary exploratory analysis, we will focus on three types of cases - Disturbance, Suspicious person, and trespass - as well as one type of case resolution - No possible action possible. The questions we want to address here include the following:
To start, we will reducing the 2019 calls for service data to the three case types of interest. The frequencies of each type are shown below in Table 1. Disturbance cases total just under 100,000, suspicious person cases amount to under 50,000, and trespass cases were just under 25,000.
| Case Type | # of Calls |
|---|---|
| Disturbance | 92,398 |
| Suspicious Person | 48,878 |
| Trespass | 24,500 |
Where are these 3 types of cases occurring?
Distribution of Cases across Seattle
Table 2 breaks down the density of calls per square mile in the city.
| Case Type | # of Calls | Calls per Sq. Mile |
|---|---|---|
| Disturbance | 92,398 | 615.22 |
| Suspicious Person | 48,878 | 325.45 |
| Trespass | 24,500 | 163.13 |
Precinct-Level Distribution
Even when we limit our focus to disturbance, trespass, and suspicious person cases, the north and west precincts lead in the number calls. Table 3 indicates that the north and west precincts together had just under 60% of all calls for the three types of cases. Further, the north had just about double the number of calls for these types of cases than the south precinct. Note: unknown is designated as the southernmost and northernmost boundaries of the city as well as the harbor areas.
| Precinct | # Calls | % |
|---|---|---|
| NORTH | 48,881 | 30.55 |
| WEST | 44,808 | 28.01 |
| EAST | 25,574 | 15.98 |
| SOUTH | 23,839 | 14.90 |
| SOUTHWEST | 16,870 | 10.54 |
| UNKNOWN | 24 | 0.02 |
The bar graph below (Figure 1) breaks down the types of cases within each precinct. Below figure 1, Table 4 presents the frequencies, percentages, and densities for each case type and precinct.
Disturbances are the majority of cases in all precincts. Although over 50% of the focal cases are disturbance in all five precincts, the northern precinct had about 4 to 5 percentage point fewer disturbance cases than the other four precincts. This seems to be driven by the fact that the northern precinct had a sizable amount of suspicious person cases - 35.5%.
The north and southwest precincts lead in the share of suspicious persons. Just over one-third of the calls in these two precincts are about suspicious persons. In fact, in the southwest precinct, there were only 4,000 fewer calls about suspicious persons than disturbances.
The western precinct has the highest number and share of trespass calls. 22% of all calls in the western precinct were reports of trespassing. Notice that in the western precinct the trespass and suspicious person calls have very similar percentages. No other precincts had two case types that were equally distributed. Lastly, the number of calls about trespassing in the western precinct - 10,216 - doubled the number of calls in each of the other precincts.
In terms of density, the east and west precincts stand out as having the highest density of calls for all three types of cases. The density of disturbance and suspicious persons calls in the east precinct edges out the density of those cases in the west. However, with trespass cases, the west precinct’s density is higher than the east precinct.
| Case | Precinct | # Calls | % in Precinct | Calls per Sq. Mi. |
|---|---|---|---|---|
| Disturbance | SOUTH | 13,873 | 58.19 | 759.06 |
| Disturbance | SOUTHWEST | 9,699 | 57.49 | 494.31 |
| Disturbance | EAST | 14,673 | 57.37 | 1,816.18 |
| Disturbance | WEST | 25,312 | 56.49 | 1,807.54 |
| Disturbance | NORTH | 25,778 | 52.74 | 740.00 |
| Suspicious Person | SOUTHWEST | 6,072 | 35.99 | 309.46 |
| Suspicious Person | NORTH | 17,286 | 35.36 | 496.23 |
| Suspicious Person | SOUTH | 7,294 | 30.60 | 399.09 |
| Suspicious Person | EAST | 6,616 | 25.87 | 818.91 |
| Suspicious Person | WEST | 9,551 | 21.32 | 682.04 |
| Trespass | WEST | 9,945 | 22.19 | 710.17 |
| Trespass | EAST | 4,285 | 16.76 | 530.39 |
| Trespass | NORTH | 5,817 | 11.90 | 166.99 |
| Trespass | SOUTH | 2,672 | 11.21 | 146.20 |
| Trespass | SOUTHWEST | 1,099 | 6.51 | 56.01 |
Sector Level Case Distribution
Interactive Map of Sector Density
The different layers show the sector density for the case types. Sectors in the core, particularly, M, K, and E have the highest densities.
Figures 2.1 through 2.3 show the number of cases in each sector. NOTE: Sector 99 - the northern and southern-most strips of land in the map - does not belong to a precinct.
Disturbances
Suspicious Person
Trespass
Beat-level distribution
Interactive Beat Density Map
Figures 3.1 through 3.3 show the number of cases in the three beats with the highest frequencies. Recall that beats are nested within sectors and sectors are nested within precincts. The letter in each of the beat names indicates the sector that the beat is located in. The color of the dot in the figures indicates the precinct the beat lies within. The 99 sector does not have beats, so it is excluded in the figures below.
Disturbances
Suspicious Person
Trespass
Resolutions by Case Type
Assistance rendered is the most common type of resolution for each of the three case types. Report written with no arrest is the next most common resolution for disturbance and trespass cases, and the third for suspicious person. Another common resolution was not being able to locate the incident/complainant, ranking third most common for disturbances, second in suspicious person cases, and fifth in trespass cases.
No police action deemed possible or necessary was fourth most common resolution for disturbance and suspicious persons cases. For trespass cases, no police action deemed possible or necessary was the sixth most common resolution with fewer than 1,000 cases.
There were some top-five resolutions that were unique to certain case types. For disturbances, responding units being canceled by the radio rounded out the top five types of resolutions. The ranking of resolutions for suspicious persons cases looked similar to disturbances. However, the suspicious persons top five was rounded out here with a written street check, though the total calls is noticeably lower than the no-police action necessary or possible resolution. The rankings for trespass cases differed from the other two types. For trespass cases, physical arrests and oral warnings were the third and fourth most common resolutions. Still, the number of trespass cases resolved with arrests and oral warnings are about one-quarter and one-tenth the number resolved by police rendering assistance.
Let’s focus on the top-5 resolutions for these cases of interest (as well as the (and no police action deemed necessary or possible for trespass, which falls just outside of the top 5). In the map series below we start to map these out.
No police action was deemed possible or necessary for 19,290 calls. There are 63 types of cases that had been deemed impossible or unnecessary for police action to be taken. In the graph below, the number of calls for each of the top 20 case types with the no police action resolution are shown. You can see disturbance and suspicious person are the top 2 most common. Disturbance calls make up about 27% of these cases and suspicious person cases are 15%. Trespass cases are in the top 20, but rank lower than our other two focal cases at 9th most frequent.
Other Thoughts:
The precinct-level map shows that the cases resolved without police action are largely in the north and west precincts.
Kernel Density
Interactive Map of Getis-Ord GI Hot Spots
The hot spots (and few cold spots) are a little harder to see in an interactive map. They are more localized because I used a 1/8th square mile pixel grid in build the raster. Pan and Zoom in to the different beats to see where the “hot spots” are located (e.g., near parks, transit stations, etc.)